Garage Concrete Pad

I'm going to be building a 26'x34' shop. I want to do the site prep, forming, rebar and insulation myself. I'm going to get my foundation contractor to place and finish the conrete. What is the best way to start? I need a 1' thickened edge (1'x1') and am having a 4" slab. Do I lay my sub base out 26x34 and hand dig out the thickened edge? Or place my forms and compact the sub base in the middle after?

Be nice I'm learning...lol
Thanks.

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Garage Concrete Pad

Why would you not be asking these question to the man that's going to be finishing your concrete?
There far more likly to know what your local codes and soil conditions area.
Around here we have to do a stem wall. Main reason is then the walls will be at least 6" above grade so the siding does not rot out' and less likly to end up with termite damage.
It also makes it so if you wanted to you could hose out the inside with no damage.

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Garage Concrete Pad

As Joe says... best to coordinate with your concrete contractor....

But I'm interested in what this reinforced edge for a SOG is all about.... around here we are same as Joe, we pour a stemwall (with spread T footer) for a garage slab. Besides getting 6" above grade exterior... you get a garage curb so your plate is not sitting in damp garage floor conditions.

So where is this perimeter reinforced slab applicable (I guess you could think of it as a 1' foot deep stem wall mono-pour.... sorta)

Garage Concrete Pad

both responders address important points but i pick'd up on something else,,, ' do the site prep, forming, rebar and insulation myself ',,, WHY the mention of rebar since no one, especially aci, recommends it in a 4" slab ? yes, they do spec 2 bars in a turned down edge but that's it.

Garage Concrete Pad

I know what the local codes are. I was mistaken in my first post. Up to 900 sqft I need a 6" slab with a 1' thinckened edge. Rebar 10M at 18" O/C. Insulation under the 6" slab (can't put under thickened edge) and insulation vertically around the ouside of the pad and out horizontally to prevent frost. This is seperate from my house build and I wanted to do most of it myself (except the concrete). Just looking for tips on how to get the thickened edge with the sub base compacted.

Garage Concrete Pad

I don't personally see anything wrong with any part of your plan, we do it in a similar fashion here all the time. As for 6" of protection from the soil, there's no reason you can't pour a curb on top of the slab at the same time, or lay a course of block afterwards. Both are very common here.

As for your actual questions, we always level the perimeter to the grade beam height, compact the perimeter, set forms on 3 sides, install gravel in center form open side, compact in 4" lifts, using the forms to establish finish grade........

Garage Concrete Pad

Quote:

Originally Posted by jomama45

I don't personally see anything wrong with any part of your plan, we do it in a similar fashion here all the time. As for 6" of protection from the soil, there's no reason you can't pour a curb on top of the slab at the same time, or lay a course of block afterwards. Both are very common here.

As for your actual questions, we always level the perimeter to the grade beam height, compact the perimeter, set forms on 3 sides, install gravel in center form open side, compact in 4" lifts, using the forms to establish finish grade........

Jomama.... Thanks... You guys are in freeze country like me and I've not really encountered this assembly for a SOG in freeze country....

Garage Concrete Pad

cheapcharlie.....like you, I'm a cheap ba$tard....actually, poor is more accurate.....

Click on the garage build link in my signature and you see some pics of my garage build including the foundation. I highly suggest building a stem wall to put your walls on. Not only will it get your wood up above the wet ground, it does a great job of keeping water out of the garage.

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Garage Concrete Pad

Jomama.... Thanks... You guys are in freeze country like me and I've not really encountered this assembly for a SOG in freeze country....

it's sort of is a "floating slab" is it not.... ?

is it restricted to non-attached structures?

and does the insulation serve a non-frost heaving solution???

Best

Peter

What the OP is looking to construct is more likely to fall into the category of an "Alaska Slab", as it relies on the foam on the exterior (horizontally) to limit frost penetration. Here, it's rare to install the exterior foam, and yes, it's nothing more than a floating slab. And yes, this type of foundation is typically limited to detached structures only, although in 20+ years of concrete/masonry work, I have done one legit job that involved tying an existing grade beam slab to a new foundation with frost walls. Lots of work, not typically worth it, but in that one scenario, it made the most sense. ANd we're no strangers to frost here, it's not uncommon for a sewer lateral to freeze here at 5' depth if it's through a driveway and on the North side of a building........

Garage Concrete Pad

Quote:

Originally Posted by jomama45

What the OP is looking to construct is more likely to fall into the category of an "Alaska Slab", as it relies on the foam on the exterior (horizontally) to limit frost penetration. Here, it's rare to install the exterior foam, and yes, it's nothing more than a floating slab. And yes, this type of foundation is typically limited to detached structures only, although in 20+ years of concrete/masonry work, I have done one legit job that involved tying an existing grade beam slab to a new foundation with frost walls. Lots of work, not typically worth it, but in that one scenario, it made the most sense. ANd we're no strangers to frost here, it's not uncommon for a sewer lateral to freeze here at 5' depth if it's through a driveway and on the North side of a building........